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Effect of sagittal alignment on spinal cord biomechanics in the stenotic cervical spine during neck flexion and extension. Biomech Model Mechanobiol 2024 Oct;23(5):1757-1764

Date

07/14/2024

Pubmed ID

39003653

DOI

10.1007/s10237-024-01866-y

Scopus ID

2-s2.0-85198355255 (requires institutional sign-in at Scopus site)

Abstract

Spinal cord stress and strain contribute to degenerative cervical myelopathy (DCM), while cervical kyphosis is known to negatively impact surgical outcomes. In DCM, the relationship between spinal cord biomechanics, sagittal alignment, and cord compression is not well understood. Quantifying this relationship can guide surgical strategies. A previously validated three-dimensional finite element model of the human cervical spine with spinal cord was used. Three models of cervical alignment were created: lordosis (C2-C7 Cobb angle: 20°), straight (0°), and kyphosis (- 9°). C5-C6 spinal stenosis was simulated with ventral disk protrusions, reducing spinal canal diameters to 10 mm, 8 mm, and 6 mm. Spinal cord pre-stress and pre-strain due to alignment and compression were quantified. Cervical flexion and extension were simulated with a pure moment load of 2 Nm. The Von Mises stress and maximum principal strain of the whole spinal cord were calculated during neck motion and the relationship between spinal cord biomechanics, alignment, and compression was analyzed using linear regression analysis. Spinal cord pre-stress and pre-strain were greatest with kyphosis (7.53 kPa, 5.4%). Progressive kyphosis and stenosis were associated with an increase in spinal cord stress (R2 = 0.99) and strain (R2 = 0.99). Cervical kyphosis was associated with greater spinal cord stress and strain during neck flexion-extension and the magnitude of difference increased with increasing stenosis. Cervical kyphosis increases baseline spinal cord stress and strain. Incorporating sagittal alignment with compression to calculate spinal cord biomechanics is necessary to accurately quantify spinal stress and strain during neck flexion and extension.

Author List

Gundamraj S, Devaraj KB, Harinathan B, Banerjee A, Yoganandan N, Vedantam A

Authors

Anjishnu Banerjee PhD Associate Professor in the Data Science Institute department at Medical College of Wisconsin
Aditya Vedantam MD Associate Professor in the Neurosurgery department at Medical College of Wisconsin
Narayan Yoganandan PhD Professor in the Neurosurgery department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Biomechanical Phenomena
Cervical Vertebrae
Finite Element Analysis
Humans
Kyphosis
Neck
Range of Motion, Articular
Spinal Cord
Spinal Stenosis
Stress, Mechanical